Conventionally, usually one of two methods is used to generate zeolite from the ashes of municipal waste that has been incinerated: (1) a boiling non-pressure method, wherein the aforementioned ashes are introduced into a tank into which is put a sodium hydrate of 2 N and a temperature of 100° C. and then mixed so as to generate zeolite in about six hours, and (2) an autoclave method, wherein the ashes are introduced into a high-temperature autoclave, whose temperature is 174° C. and whose pressure is about 8 kgf/cm2, and sodium hydrate of 3.5 N is added and mixed with the ashes so as to generate zeolite in about three hours. FIG. 11 is a table that compares several conventional artificial-zeolite manufacturing facilities. In FIG. 11, “Planned Annual Production” means the planned production volume, except for Facility A. None of the facilities referred to in FIG. 11 can continuously manufacture a large amount of zeolite. Generally speaking, because three processes of separating solids from liquid are required in one production line, it is necessary to use equipment that can perform all three processes, i.e., a solid-liquid separator (that consists of a super-decanter, a centrifugal separator, and a filter press), resulting in high facility costs.
As a problem to be overcome, some chemical substances such as dioxins, PCBs, and heavy metals, which typically are contained in the aforementioned ashes, are highly toxic and adversely affect the environment, thereby causing damage. Therefore, there is a demand for a technique by which to separate, recover, and reuse the above toxic substances in a safe form. For example, when using a thermal dissolving-and-recovery device that utilizes a method for circulating—through a pipe in a heating medium—a solution containing toxic substances, a large amount of energy is spent for heating the heat solvent, and the efficiency of the heat exchanger is extremely poor.
There are two types of methods for separating substances: physical separating methods and chemical separating methods. One advantage of the physical separating method is that no secondary chemical treatment is needed. In a physical separating method, when magnetic separation is performed, it is possible to separate and recover, at high speed, a large amount of microparticles (of atomic/molecular-size) of substances from a suspension liquid in which such microparticles are suspended.
In a physical separating method, it has been discovered that it is possible to attract paramagnetic substances, and even diamagnetic substances, in a ferromagnetic field.
The specific magnetic susceptibilities of diamagnetic substances such as water and silica glass, and of paramagnetic substances such as aluminum and oxygen, are 10−3 to 10−4, which are 1/106– 1/107 times as small as the magnetization intensity of ferromagnetic substances, which is 103. Therefore, the energy of said nonmagnetic substances have conventionally been recognized as so small that it can be ignored.
Magnets that typically are used in our daily lives have a magnetism of about 100 gauss (which equals 0.01 T [tesla]). The magnetism of a magnet that has a magnetic field of 10 T is 103 times larger than that of a typical daily-use magnet. Because magnetic energy is proportional to the square value of the magnetism of a magnetic field, nonmagnetic elements can be separated in a ferromagnetic field that exceeds 10 T.
As a magnetic system for separating and removing substances by a magnetic force, there has conventionally been used a system wherein (1) plural solenoid coils of different magnetic strengths are parallelly installed on the outside of a separating cylinder, and (2) plural separating cylinders are parallelly arranged so as to separate and recover substances that are desired to be magnetically attracted, separated, and recovered. Such a system is disclosed in Japanese Published Patent Application No. 2000-296303.